1. Field of the Invention
The present invention relates to oxygen concentrator systems, and more particularly, to a patient ventilator oxygen concentrator system having altitude compensation to improve performance at higher altitudes.
2. Description of the Related Art
Many medical applications exist that require either oxygen-enriched air or medical grade air. Both are widely used in respiratory care treatments, for example. Furthermore, both oxygen-enriched air and medical grade air are used to power various pneumatically driven medical devices.
Hospitals and other medical care facilities have a need for both oxygen-enriched air and medical grade air. In military hospitals and in hospitals in Europe, for example, these needs may be met by using oxygen concentration systems to provide oxygen-enriched air and by using a filtration system for providing medical grade air. On the other hand, hospitals and other medical care facilities in the United States often use high-pressure gas systems or liquid oxygen to gaseous conversion systems to provide oxygen-enriched air.
Commonly used oxygen concentration systems often employ a pressure swing adsorption (PSA) process to remove nitrogen from a given volume of air to produce oxygen-enriched air. Such a process is disclosed in U.S. Pat. No. 4,948,391 to Noguchi and this patent is incorporated herein by reference in its entirety.
In such oxygen concentration systems, as the plenum pressure is increased, the product flow, that is, the oxygen-enriched air, is decreased and the oxygen concentration increased. Accordingly, at low plenum pressures, the oxygen concentration of the oxygen-enriched air may be insufficient and at high plenum pressures the product flow output may be insufficient.
The co-pending related application discloses an oxygen concentration system which obviates many of the disadvantages noted above. However, the oxygen concentration system of the co-pending related application suffers from performance degradation at higher altitudes.
It is an object of the present invention to provide an oxygen concentrator system which utilizes at least one oxygen concentrator subsystem having altitude compensation and a plenum to provide an oxygen-enriched air output.
It is a further object of the present invention to provide an oxygen concentrator system as above and including a plenum charging system to meter and to control the flow of oxygen enriched air between the at least one oxygen concentrator subsystem and the plenum and to allow the flow of oxygen enriched air only from the at least one oxygen concentrator subsystem to the plenum.
It is another object of the present invention to provide an oxygen concentrator system as above and further including a discharging check valve to selectively allow the plenum reserve capacity to flow out only during a high demand oxygen flow.
It is yet another object of the present invention to provide an oxygen concentrator system as above and further including a plenum bypass value to make the transient response faster and to avoid overdrawing the at least one oxygen concentrator subsystem so as to keep the oxygen concentration of the oxygen-enriched air above a predetermined minimum value.
These and other objects of the present invention may be achieved by providing an oxygen concentrator system with altitude compensation, the system comprising: a system air inlet to receive supply air; at least one system outlet to output oxygen-enriched air; at least one oxygen concentrator subsystem comprising a pair of oxygen PSA (Pressure Swing Adsorption) beds and including an input to receive supply air from the system air inlet and an output to output oxygen-enriched air to the at least one system outlet; a plenum and a plenum charging system located between the output of the at least one oxygen concentrator subsystem and the at least one system outlet, the plenum charging system selectively enabling oxygen-enriched air to flow from the at least one oxygen concentrator subsystem to the plenum; an optional plenum bypass valve to selectively bypass the plenum so as to enable oxygen-enriched air to flow from the at least one oxygen concentrator subsystem to the at least one system outlet; an absolute pressure transducer to provide an electrical signal indicative of a measured ambient barometric pressure; and a monitor/controller to receive the electrical signal from the absolute pressure transducer and to control cycle times of the pair of oxygen PSA beds based on the measured ambient barometric pressure.
The foregoing and other objects may be achieved by providing a method of increasing oxygen concentration, the method comprising: receiving supply air from a system air inlet at an input of at least one oxygen concentrator subsystem comprising a pair of PSA (Pressure Swing Adsorption) oxygen beds and outputting oxygen-enriched air to at least one system outlet; selectively enabling oxygen-enriched air to flow from the at least one oxygen concentrator subsystem to the plenum; optionally selectively bypassing the plenum to enable oxygen-enriched air to flow from the at least one oxygen concentrator system to the at least one system outlet; measuring ambient barometric pressure and providing an electrical signal indicative of the measured ambient barometric pressure; and controlling cycle times of the pair of PSA oxygen beds with a monitor/controller based on the signal representative of the ambient barometric pressure.
The foregoing and a better understanding of the present invention will become apparent from the following detailed description of an example embodiment and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the foregoing and following written and illustrated disclosure focuses on disclosing an example embodiment of the invention, it should be clearly understood that the same is by way of illustration and example only and that the invention is not limited thereto. This spirit and scope of the present invention are limited only by the terms of the appended claims.